JPH11206710A - Ophthalmological device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate alignment detection by projecting an alignment index to the cornea of an eye to be examined from an index projection means, detecting a luminescent point equal to or higher than a prescribed luminance level, then removing irregular luminescent point and moving a measurement part. SOLUTION: When the detection of an alignment index image becomes possible by video signals from a CCD camera 16, a control circuit 70 drives an X axis motor 74 and a Y axis motor 75 based on the position information and moves the measurement part so as to attain an alignment completion state in an XY direction. Then, by output signals from the CCD camera 16, luminance signals equal to or higher than a prescribed threshold value are detected and the irregular luminescent points in them are obtained and removed. Based on the result, the measurement part is moved to the eye to be examined. In such a manner, the alignment detection is quickly and highly accurately performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmologic apparatus for aligning a device with a subject's eye in a predetermined positional relationship.

[0002]

2. Description of the Related Art In an ophthalmologic apparatus such as an eye refractive power measuring apparatus and a non-contact tonometer, the measurement is performed by adjusting the alignment of a measuring optical system of the apparatus with respect to an eye to be examined in a predetermined positional relationship. As an alignment mechanism, one that detects an alignment index projected on the cornea of the eye to be inspected, and drives and controls a moving unit that moves the apparatus based on the detected information, thereby automatically adjusting or tracking the alignment is proposed. ing. The alignment index used for the drive control of the apparatus projects an index light beam from the front of the subject's eye to form a bright point at the apex of the cornea, and projects a plurality of alignment indices based on the positional relationship of the bright points formed on the cornea. In some cases, the center of the cornea is detected.

[0003]

However, a large number of scattered lights appear as bright spots on the corneal surface due to the condition of the corneal surface, other light-emitting materials (fluorescent lamps, etc.) and the tears of the subject. In some cases, the corneal center cannot be detected without being distinguished from the alignment index. In such a case, the apparatus cannot judge an erroneous alignment state or cannot detect the alignment itself. Also,
When the bright spot information is sequentially stored in the memory, if a large number of bright spots are detected by the scattered light, the detection may exceed the allowable range of the memory and may be stopped halfway.

The present invention has been made in view of the above-mentioned problems of the prior art,
An object of the present invention is to provide an ophthalmologic apparatus capable of easily performing alignment detection while minimizing the influence of scattered light.

[0005]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) In an ophthalmologic apparatus having a measuring section for inspecting and measuring an eye to be inspected and aligning the measuring section at a predetermined position with respect to the eye to be inspected, a plurality of alignment indices having a predetermined arrangement relationship with the cornea of the eye to be inspected. Index projecting means for projecting an image, a bright spot detecting means for detecting a bright spot having a predetermined brightness level or more formed on the cornea of the eye to be inspected, and an irregular spot for detecting an irregular bright spot based on the detected bright spot information. Bright spot detection means,
And moving instruction means for instructing the eye to move the measuring unit based on the bright spot information excluding the irregular bright spot.

(2) In the ophthalmologic apparatus according to (1), when the irregular bright spot detecting means shows an abnormal distribution in a predetermined area, the irregular bright spot detecting means detects the irregular bright spot. It is characterized in that it comprises a judging means for judging the bright spots inside as irregular bright spots.

(3) In the ophthalmologic apparatus according to (1), the irregular bright point detecting means determines whether or not the detected number of bright points exceeds a predetermined amount, and the irregular bright point detecting means includes: Second determining means for determining whether the distribution of the bright spots is within a predetermined frame, wherein the number of bright spots exceeds a predetermined amount by the first determining means and the distribution of the bright spots is determined by the second determining means. When it is determined that the bright spot falls within the frame, the bright spot up to the position where the predetermined amount is counted sequentially from the vertical direction of the eye to be inspected is set as an irregular bright spot.

(4) In the ophthalmologic apparatus according to (1), if effective information is not obtained as a result of excluding the irregular bright spot detected by the irregular bright spot detecting means, the movement instructing means sets the movement instructing means. It is characterized in that a movement instruction is issued based on previously obtained bright spot information.

(5) In the ophthalmologic apparatus according to (1), when effective information is not obtained as a result of excluding the irregular bright points detected by the irregular bright point detecting means, a notification to that effect is given. It is characterized by comprising means.

(6) In the ophthalmologic apparatus according to (1), the irregular bright spot detecting means includes a storage means for storing position information of the detected bright spot, and the stored bright spot position information is stored in a predetermined amount. First determining means for determining whether or not the bright spot position information has exceeded a predetermined amount, and further determining whether or not the distribution of the bright spots is within an area of a predetermined size. And if the distribution of the bright spot positions is determined to be within a predetermined size, the distribution area of the bright spot positions is determined to be an irregular bright spot area. An irregular bright spot area determining means.

(7) The ophthalmologic apparatus according to (1) is further provided with control means for controlling the movement of the measuring section by the movement means based on the movement instruction signal of the movement instruction means.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings, taking a non-contact type tonometer as an apparatus of an embodiment.

[Overall Configuration] FIG. 1 is a schematic diagram showing an outline of a non-contact tonometer according to an embodiment. Reference numeral 1 denotes a base, on which a chin rest 2 for fixing an eye to be examined is fixed. 3
Is a main unit, 4 is a measuring unit that houses an optical system described later, and 5 is a joystick for moving the main unit 3 and the measuring unit 4. By operating the joystick 5, the main unit 3 slides on the horizontal plane of the base 1 in the front-rear direction (Z direction) and the left / right direction (X direction) with respect to the examiner, and the measuring unit 4 moves up and down with respect to the main unit 3. Move in the direction (Y direction).

The movement of the main body 3 with respect to the base 1 includes a spherical surface and a lower end formed below the axis of the joystick 5, a sliding plate on which the lower end slides, and the base 1 in contact with the sliding plate. Fine configuration in the horizontal direction is realized by the configuration of the attached friction plate and the spherical bearing inside the housing 3a integrated with the main body 3. The vertical movement of the measuring section 4 with respect to the main body section 3 is as follows.
The rotation direction and the amount of rotation of the rotary knob 5a are detected from the signal of the light receiving element by a light source and a light receiving element provided on a shaft with a slit plate that rotates together with the rotation knob 5a at the upper part of the outer periphery of the joystick 5 interposed therebetween. This is performed by controlling the driving of a Y-axis motor that moves the measuring unit 4 up and down based on the measurement. The details of this joystick mechanism are described in Japanese Patent Application Laid-Open No. 6-7292 (the joystick mechanism of an ophthalmologic apparatus according to the present invention) by the present applicant.

The measuring section 4 also moves in the left-right direction (X direction) and the front-back direction (Z direction) with respect to the main body section 3. These movements are performed not by the joystick 5 but by an X-axis motor and a Y-axis motor that are driven and controlled by a control circuit described later.

Reference numeral 6 denotes a nozzle section in which a nozzle for ejecting the compressed gas toward the eye to be examined is arranged. Four light sources 7a to 7d for projecting alignment indices around the cornea of the subject's eye with the nozzle 6 as the center are arranged on the subject side of the measurement unit 4. A knob 8 for restricting a movement limit at which the nozzle 6 can approach the eye to be examined is arranged on a side portion of the main body 3. Further, a TV monitor for observation is provided on the joystick 5 side (examiner side) of the main body 3.

[Optical System] FIG. 2 is a diagram showing a main part of an alignment optical system of the apparatus, as viewed from above. A non-contact tonometer measures the intraocular pressure of the subject's eye based on the gas pressure directly or indirectly detected by blowing a compressed gas onto the cornea of the subject to deform it into a predetermined shape. However, the description of the measurement mechanism itself is omitted because it has little relation to the present invention. For details, refer to JP-A-5-56931 (title of the invention, non-contact tonometer) by the present applicant.

(Observation Optical System) Reference numeral 10 denotes an observation optical system, and L1 indicates its optical axis. The observation optical system 10 is used for first and second alignment indices in up, down, left, and right directions (to be described later).
Also serves as an index detection optical system for detecting the On the optical path of the observation optical system 10, a nozzle 9 for ejecting a gas for deforming the cornea is disposed while being held by the glass plates 8a and 8b.
1 matches. A beam splitter 11, an objective lens 12, a beam splitter 14, a filter 15, and a CCD camera 16 are arranged on the optical axis L1. The filter 15 transmits light beams (wavelength 950 nm) of the first and second alignment index optical systems (described later) and the reticle projection optical system, and transmits visible light and light beams (wavelength 800 nm) of the distance index projection optical system (described later). , And prevents unnecessary noise light from entering the CCD camera 16. The anterior ocular segment image and the index image captured by the CCD camera 16 are projected on a TV monitor 17, and the examiner observes them.

(Reticle Projection Optical System) Reference numeral 20 denotes a reticle projection optical system. Reference numeral 21 denotes a reticle projection light source that emits infrared light having a wavelength of 950 nm, 22 denotes a reticle plate on which an annular mark is formed, and 23 denotes a projection lens. The reticle on the reticle plate 22 illuminated by the reticle projection light source 21 includes a projection lens 23, a beam splitter 14,
The image is received by the CCD camera 16 via the filter 15.

The luminous flux emitted from the reticle projection light source 21 is modulated at a predetermined frequency in order to make it easier for the CCD camera 16 to detect the target image, whereby the light sources 7a to 7d and The light flux emitted from the light source 31 is distinguished. Further, since the reticle image only needs to be observed on the TV monitor, the reticle image may be discriminated from the difference in luminance from the index image by reducing the amount of light,
It may be generated electrically by a generator.

(Fixation Optical System) The fixation optical system 25 has a light source 26 that emits visible light, a fixation target plate 27, and a projection lens 28. The light beam emitted from the fixation target plate 27 by turning on the light source 26 passes through the projection lens 28, the beam splitter 14, the objective lens 12, and the beam splitter 11, and enters the eye to be examined through the nozzle 9.

(First Alignment Target Projection Optical System) 3
0 indicates a first alignment target projection optical system. Reference numeral 31 denotes a light source for projecting the center target, and 32 denotes a projection lens. Light source 31
Emits infrared light having a wavelength of 950 nm. The infrared light beam emitted from the light source 31 is converted into a parallel light beam by the projection lens 32, then reflected by the beam splitter 11, and reflected by the optical axis L.
The light passes through the nozzle 9 along 1 and irradiates the cornea Ec of the eye to be examined. The light beam specularly reflected by the cornea Ec forms a first alignment index i1 which is a virtual image of the light source 31. The light flux of the first alignment index i1 forms an image of the first alignment index i1 on the image sensor of the CCD camera 16.

(Second Alignment Target Projection Optical System) The second alignment target projection optical system 7 includes four light sources 7a to 7a.
d (see FIG. 1). The light sources 7a and 7b and the light sources 7c and 7d are arranged at the same height distance with the optical axis L1 interposed therebetween, and have the same optical distance of the index. Light source 7a-
Reference numeral 7d emits infrared light having the same wavelength as that of the light source of the first alignment target projection optical system at 950 nm. The light from the light sources 7a and 7b is radiated obliquely upward toward the periphery of the cornea of the subject's eye to form indices i2 and i3, which are virtual images of the light sources 7a and 7b. The light sources 7a and 7b also function as light sources for detecting the degree of opening of the eyelids. The light from the light sources 7c and 7d is emitted obliquely downward toward the periphery of the cornea of the subject's eye to form indices i4 and i5, which are virtual images of the light sources 7c and 7d. The light sources 7a to 7d also serve as illumination light sources for illuminating the anterior segment of the subject's eye.

The luminous fluxes of the four indices i2, i3, i4, i5 enter the CCD camera 16 via the observation optical system 10,
An image is formed on the image sensor of the CCD camera 16.

(Distance Index Projection Optical System) Reference numeral 50 denotes a distance index projection optical system, and L2 indicates its optical axis. The optical axis L2 is provided to be inclined with respect to the optical axis L1, and the two optical axes intersect at a position apart from the nozzle 9 by a predetermined working distance. Reference numeral 51 denotes a distance index projecting light source that emits light having a wavelength of 800 nm different from the light sources 7a to 7d and the light source 31, and 52 denotes a projection lens.

The light emitted from the light source 51 is converted into a parallel light beam by the projection lens 52, and applied to the cornea Ec along the optical axis L2. The light beam specularly reflected by the cornea Ec forms an index i6 which is a virtual image of the light source 51.

(Distance index detecting optical system) Reference numeral 60 denotes a distance index detecting optical system, and L3 indicates its optical axis. The optical axis L3 and the optical axis L2 are axes symmetric with respect to the optical axis L1, and the optical axis L3
And the optical axis L2 intersect on the optical axis L1. Optical axis L3
A light receiving lens 61, a filter 62, and a one-dimensional detection element 63 are arranged on the upper side. The filter 62 transmits a light beam having a wavelength of 800 nm emitted from the light source 51, and
7D and a 950 nm light beam emitted from the light source 31 are opaque to light, and prevent noise light from entering the one-dimensional detection element 63.

The corneal reflected light beam of the light source 51 forming the index i6 enters the one-dimensional detection element 63 via the light receiving lens 61 and the filter 62. When the subject's eye moves in the axial direction (front-back direction) of the observation optical axis L1, the image of the index i6 also moves in the detection direction of the one-dimensional detection element 63.
The position of the eye to be inspected is detected from the deviation of the image of the index i6 on 3.

[Control System] FIG. 3 is a block diagram of a main part of a control system of the apparatus. 70 is a control circuit, 71 is an image processing circuit, 72
Is a distance index detection processing circuit. Reference numerals 74 to 76 denote X-axis, Y-axis, and Z-axis motors for driving the measuring unit 4 with respect to the main body 3, and 77 to 79 denote driving circuits for the respective motors. 80
Denotes a measurement system, 81 denotes a display circuit for generating character information, figures, and the like, and 82 denotes a synthesis circuit. Reference numeral 83 denotes an alignment mode changeover switch for selecting whether the alignment is to be performed by the apparatus based on the detection of the index, or to be performed by the examiner using only the joystick 5. 8
Reference numeral 4 denotes a measurement switch for inputting a measurement start signal.

The image processing circuit 71 performs image processing on the captured image from the CCD camera 16 and inputs the processing result to the control circuit 70. The control circuit 70 obtains the target image position information and the pupil position information from the input signal.

The control circuit 70 obtains information on the deviation of the eye E in the front-rear direction based on the signal from the one-dimensional detection element 63 input through the detection processing circuit 72. The deviation information obtained by the control circuit 70 is sent to a display circuit 81, and based on the information, the display circuit 81 outputs a graphic signal of a distance mark and a T signal.
A position signal on the V monitor 17 is generated. The output signal from the display circuit 81 is combined with the video signal from the CCD camera 16 by the combining circuit 82 and output to the TV monitor 17.

FIG. 4 is a diagram showing an example of a screen displayed on the TV monitor 17 when the alignment is performed in a proper state in the XY directions. In the state where the X and Y directions are aligned properly, the four index images i20, i30 and i4 formed around the cornea by the second alignment index projection optical system.
0, i50 and an index image i10 formed near the center of the cornea by the first alignment index projection optical system are projected. 41
Indicates a reticle image. Reference numeral 42 denotes a distance mark. The distance mark 42 moves up and down on the reticle image 41 in real time in accordance with the distance between the cornea of the eye to be inspected and the nozzle portion 6, and when the cornea is at an appropriate working distance. It overlaps the image 41.

The operation of the apparatus having the above configuration when the automatic alignment mode is selected will be described. The examiner fixes the subject's eye using the chin rest 2 and causes the subject's eye to fixate on the fixation target. When the preparation for measurement is completed, the examiner observes the TV monitor 17, operates the joystick 5 and the like so that the anterior eye image and the alignment index image appear, and roughly aligns the measurement unit 4 with the subject's eye.

When the control circuit 70 can detect the alignment index image based on the video signal from the CCD camera 16, the control circuit 70 controls the driving of the X-axis motor 74 and the Y-axis motor 75 based on the positional information, and controls the measuring section 4 to operate. It moves so that the alignment in the XY directions is completed. A process of detecting a bright point of an alignment index image (hereinafter, also simply referred to as an index image) based on an output signal from the CCD camera 16 will be described (see a flowchart of FIG. 6). An image signal for one screen from the CCD camera 16 is transmitted to an image processing circuit 71.
, A bright spot detection process is performed. The bright spot detection starts from the coordinate position of the upper left (x, y) = (0, 0) of one screen (STEP-1 to STEP-3), and the lower right of the screen (x, y) = (xlim, ylim). The detection proceeds toward (STEP-9 to STEP-12). During this time, if luminance signal data equal to or greater than a predetermined threshold value can be detected (STEP-4), a bright-spot edge, which is a bright-spot rising position signal (even if all y signal positions are not stored, each y signal can be detected by a rising signal). When the counted number of bright spot edges falls within a predetermined stock capacity (for example, 100), the coordinate position is stored (STEP-5). ~ STEP-8). When the counted number of edges falls within the predetermined stock capacity and the detection is completed until (x, y) = (xlim, ylim) (STEP-11), the data is stored in the data memory. An individual position of each luminescent spot is calculated based on the obtained luminescent spot edge position information. Each bright spot has a size, but its individual position can be calculated by taking the center of the bright spot edge positions on the continuous y coordinate (STEP-13). After the individual position of each bright spot is calculated, the bright spot due to the scattered light is distinguished from the bright spot of the alignment index image to specify the position of the alignment index image (STEP-14). The specification of the alignment index image will be described. First, the positional relationship between each index image as a basis for specifying the alignment index image will be described with reference to FIG. FIG. 5 shows a positional relationship of an index image formed by each alignment light when the eye to be examined having a certain reference corneal curvature is aligned in an appropriate state. With respect to the index image i10 when aligned in an appropriate state,
It is assumed that the index images i40 and i50 are separated from each other by a substantially width a in the downward direction of the Y axis, and are separated by a substantially width c on both sides in the X axis direction. In addition, the index images i20 and i30 are substantially separated from each other by a width a in the upward direction of the Y-axis, and are substantially smaller than the width c on both sides in the X-axis direction (not to be half of the width c). It is assumed that they are positioned apart by the width b. The positional relationship and the interval do not fluctuate greatly, although there are some changes depending on the corneal shape and the relative position of the apparatus with respect to the eye to be inspected. It is possible to distinguish between a bright spot and an index image by light, and to specify the index image. For example, as shown in FIG. 7, it is assumed that bright spot groups 104 and 105 in which bright spots 101 to 103 apart and a large number of bright spots are collected are detected. The bright spot groups 104 and 105 appear as bright spots scattered by the lights of the alignment light sources 7c and 7d due to factors such as tears of the eye to be examined. The positional relationship and distance of each bright point are sequentially observed for each bright point, and by comparing with the positional relationship of the index images in FIG. 5, those having a low possibility of being alignment index images are sequentially deleted. In the example of FIG.
Can be specified as index images i10, i20, and i30, respectively. The index image i in the bright spot groups 104 and 105
There is also a possibility that there are bright spots of 40 and i50, but if any of them cannot be determined, it is not specified and is not used as alignment information. When the alignment index image can be specified, the control circuit 70 controls the movement of the measuring unit 4 based on the number and the positional relationship of the index images to perform alignment (STEP-15). This method will be described later. STE in FIG.
The case where the number of bright spot edges written in the data memory in P-6 exceeds a predetermined stock capacity range will be described. In this case, look at the distribution of the bright spot edge positions. The distribution of the bright spot edge positions can be determined from the number of y-coordinate lines from the bright spot edge position detected first (STEP-16).
If this number does not exceed a preset number (hereinafter referred to as a set line number LN), the y coordinate of the bright spot detection is updated to y + 1 from the y coordinate where the number of bright spot edges exceeds a predetermined stock capacity. After that (STEP-18), the process returns to STEP-2 to count the number of bright spot edges stored in the data memory and initialize the address of the coordinates. Then, STEP-3 mentioned above
~ Repeat the process of STEP-12. At this time, by overwriting the coordinates of the bright spot edge position stored in the data memory, data in the range of the set number of lines LN is sequentially deleted from the data memory. Here, the set line number LN
Is set to a range slightly wider than the range in which the index images i10, i20, and i30 or the index images i10, i40, and i50 shown in FIG. 5 can be detected (considering individual differences in the eye to be examined).
This is because, even if there are bright spots due to scattered light, if at least these three alignment index images can be specified, the measurement unit 4 can be guided based on the number and positional relationship of index images described later. For example, when scattered light is generated on the cornea surface by a fluorescent lamp or the like, bright spots may be concentrated on the screen above the eye to be examined. In this case, since the data of the bright spot edge exceeds the stock capacity of the memory and the bright spots are concentrated, the distribution is the set number of lines LN.
Below. Therefore, the concentrated data is deleted, and only the alignment index image detected in the area below the concentrated data is specified. Conversely, if the number of lines from the first detected bright spot edge position exceeds the set number of lines LN, the detection on this screen ends, and the bright spot edge position information ( Or, based on the movement amount information), the individual position of each luminescent spot is calculated, the alignment index image is specified, and the alignment is executed (STEP-13 to STEP-15 described above). For example, in the example shown in FIG. 7, when there are a large number of bright spots in the bright spot groups 104 and 105, the stock capacity of the memory is exceeded during this process. At this time, the number of detection lines at the y coordinate is the set number of lines L
Therefore, the calculation of the individual position of each luminescent spot and the identification of the index image are performed in this range. In the above embodiment, the number of bright spot edges is counted, and it is determined whether the number has reached a predetermined stock capacity.
As in EP-13, each bright spot having a size is counted as a number, and the number and distribution may be used to determine STEP-16 or later. The guidance of the measuring unit 4 based on the number of (identified) index images and the positional relationship will be described with reference to FIGS. Note that the order of the index images used in the following description is sequentially from the top to the bottom of the screen, and those having the same height are arranged on the left.

<When the index image is one out of five> The measuring unit 4 is moved only when the detected index image can be identified as the index image i10, and when the detected index image cannot be identified as the index image i10, the measuring unit 4
Is not moved. When the detected index image satisfies the following condition, the index image can be specified as the index image i10.

I. The detected index image exists within a predetermined range (for example, within a size corresponding to the diameter of the nozzle 9) around the reference position.

II. In addition, the deviation in the Z direction with respect to the appropriate working distance is within a predetermined range (the image of the index i6 by the distance index projection optical system 50 can be detected by the primary detection element 63, and the deviation is within the predetermined range. ).

<When the number of target images is two out of five> [A] The difference between the X coordinates of the first and second target images is small (width b or less) and the Y of the first and second target images is small. When the difference between the coordinates is large (substantially 2a): As shown in FIGS. 8A and 8B, the combination of the index images i20 and i40 and the index image i3
There are two combinations of 0 and i50. Further, these two types are distinguished as follows. I. When first X coordinate> second X coordinate: index image i
30, i50 can be determined. II. In case of first X coordinate <second X coordinate: index image i
20, i40 can be determined.

[B] When the difference between the Y-coordinates of the first and second index images is substantially the same: As shown in FIGS. 9A and 9B, the combination of the index images i20 and i30 and the index image i40, There are two combinations of i50. Further, these two types are distinguished as follows. I. When the difference between the first and second X coordinates ≦ the width 2b: it can be determined that the target images are i20 and i30. II. When the difference between the first and second X coordinates> the width 2b: it can be determined that the target images are i40 and i50.

[C] A case where the difference between the Y coordinates of the first and second index images is substantially a and only the first index image is within a predetermined range around the reference position (center optical axis). : FIG.
As shown in (a) and (b), there are two combinations of the index images i10 and i40 and the combination of the index images i10 and i50, and the first one can be specified as the index image i10.

[D] A case where the difference between the Y coordinates of the first and second index images is substantially a and only the second index image is within a predetermined range around the reference position (center optical axis). : FIG.
As shown in (a) and (b), there are two types of combinations of the index images i10 and i20 and the combination of the index images i10 and i30, and the second one can be specified as the index image i10.

[E] The difference between the X-coordinates of the first and second index images is not substantially the same, and Y is the difference between the first and second index images.
When the difference between the coordinates is large (approximately 2a): FIG.
As shown in (b), a combination of the index images i20 and i50,
There are two combinations of the index images i30 and i40. A method of guiding the measuring unit 4 based on the index image pattern that can be specified as described above and its positional relationship will be described. First, when the index image i10 is a pattern that can be specified as in [C] and [D], the measuring unit 4 is guided based on the pattern. When the index image i10 cannot be specified, the XY coordinates of the center of the cornea are determined from the two index images, and the measuring unit 4 is guided based on the coordinate position. For example, the I.D. The Y coordinate of the cornea center when the index images i30 and i50 can be specified as described above can be determined by "(Y1 + Y2) / 2". On the other hand, if the X coordinate is considered based on the index image i30,
The coordinates of the width b are added to the coordinates X1 and can be determined for the time being by "X1 + b". However, this tends to be inaccurate due to individual differences in corneal size. The coordinate position of each index image changes substantially in proportion to the change in the corneal curvature. X
Using this relationship, the coordinates are multiplied by a constant α in the Y coordinate interval between the index images i30 and i50 instead of the coordinates of the width b, and this is added to the X coordinate X1 of the index image i30 (or X2 which is the X coordinate of the index image i50). That is, the X coordinate in this case is “X1 + (Y2-Y1) ×
α ”. By doing so, it is possible to determine the coordinates of the corneal center position with higher accuracy than when simply adding a constant. The value of the constant α is set in advance from the relationship between the arrangement of the index projection system and the detection system. Similarly, [A] II. The XY coordinates of the center of the cornea when the index images i20 and i40 can be specified as (X1- (Y
2−Y1) × α, (Y1 + Y2) / 2). Also,
Based on the same idea, the XY coordinates of the corneal center when the index images i20 and i30 of [B] can be identified as ((X1 + X
2) / 2, Y1 + (| X1−X2 |) × β).
II of [B]. The XY coordinates of the corneal center when the index images i40 and i50 can be specified as ((X1 + X2) / 2, Y1-
(| X1−X2 |) × γ). Where the constants β and γ
Is also set in advance from the relationship between the arrangement of the index projection system and the detection system.

As shown in [E], when the combination of the index images i20 and i50 and the combination of the index images i30 and i40 can be specified, the XY coordinates of the corneal center are ((X1 + X2) / 2,
(Y1 + Y2) / 2).

As described above, the index image that can be detected is 2
However, if the index image i10 can be determined, the measurement unit 4 is guided based on the index image i10 based on the corneal center position obtained from the two index images if the index image i10 cannot be identified. As a result, the measuring unit 4 always moves so that the central axes of the measuring unit 4 coincide with each other. Thereby, the guidance of the measuring unit 4 is stabilized.

<When the number of index images is three out of five> When three or more index images are detected, the index image i10
To i50. The control circuit 70 determines the XY coordinates (X1, Y1) of the first index image,
By obtaining the XY coordinates (X2, Y2) of the third index image and the XY coordinates (X3, Y3) of the third index image, the measurement unit 4 is moved as follows.

[A] When the difference between the Y-coordinates of the first and second index images is approximately 2a: There are two types shown in FIG.
In this case, although the index image i10 is not detected, the control circuit 70 determines that the corneal center is at the XY coordinates ((X2 + X
3) / 2, and the measurement unit 4 is moved assuming that (Y1 + Y2) / 2).

[B] When the difference between the Y-coordinates of the first and second index images is substantially a and the second and third Y-coordinates are substantially the same: This is the case shown in FIG. It is. Since the first one can be specified as the index image i10, the measuring unit 4 is moved based on this.

[C] The Y coordinate of the first and second index images is substantially the same, and the difference between the Y coordinate of the second and third index images is approximately 2
In the case of a: There are two types shown in FIG. FIG.
As in the case of (a), the index image i10 is not detected, but the corneal center is located at the XY coordinates ((X1 + X2) / 2, (Y1
+ Y3) / 2), and the measurement unit 4 is moved.

[D] When the difference between the Y-coordinates of the second and third index images is substantially a and the first and second Y-coordinates are substantially the same: this is the case shown in FIG. Is. Since the third image can be specified as the index image i10, the movement of the measuring section 4 is controlled based on this.

[E] When the above conditions A to E are not satisfied: There are four cases shown in FIG. in this case,
Since the second index image can be specified as the index image i10, the movement is performed based on this.

<When the number of target images is four out of five> The control circuit 70 obtains the XY coordinates of each target image and obtains the measuring unit 4 as follows.
Make a move.

[A] When the Y-coordinates of the first and second index images are not substantially the same: There are two cases shown in FIG. Since the second image can be specified as the index image i10, the movement is performed based on this.

[B] Case where the Y-coordinates of the third and fourth index images are not substantially the same: There are two cases shown in FIG. Since the third one can be specified as the index image i10, the movement is performed based on this.

[C] In the case of conditions other than A and B: FIG.
4 (c). This is because only the index image i10 is not detected, so that the corneal vertex is the midpoint of the four index images, for example, ((X1 + X2) / 2, (Y1 + Y3) /
The movement of the measuring unit 4 is performed as in 2).

<When the number of index images is 5 out of 5> Since all the index images have been detected and the index image i10 can be specified, the measuring unit 4 is moved based on this.

The method of guiding the measuring section 4 based on the number and positions of the detected index images (basically the same as that described in Japanese Patent Application No. 9-137527 by the present applicant) has been described above. In any case, when the index image i10 is detected and specified, the reference image is used as a reference. When the index image i10 cannot be detected and specified, the movement is performed based on the coordinates of another index image. In addition, the final determination of the alignment state in the XY directions can be determined that the alignment is completed if the detected and specified index image i10 is within a predetermined allowable range, even if all five index images are not detected. . The index image i1 at this time
The position detection of 0 calculates not only the rising position of the y-coordinate but also the center of the luminescent spot precisely by edge processing or the like. By repeating the above detection process for each image signal for one screen, the measuring unit 4 is moved so that alignment can be completed if the bright spot of the index image can be specified even if there is a bright spot due to scattered light. When the bright spot of the index image is not specified, the measuring unit 4 is continuously moved based on the information obtained before. If alignment cannot be performed because the bright spot of the index image cannot be specified within a certain period of time, a message to that effect may be displayed on the screen of the monitor 17 and the examiner may be prompted to operate the joystick. The movement of the measuring unit 4 causes the index image i1
If 0 falls within a predetermined allowable range, the alignment in the XY directions is completed. One-dimensional detection element 6
The measuring unit 4 is moved after obtaining the shift amount based on the signal from the measuring unit 4. When the alignment in both the XY direction and the Z direction is completed, the control unit 70 automatically issues a measurement start signal and executes the measurement by the measurement system 80. In the above embodiment, C
The bright point detection is performed after the image signal from the CD camera 16 is temporarily stored in the image memory in the image processing circuit. However, the bright point may be directly detected from the image signal from the CCD camera 16. good. An example of this case will be described with reference to FIG. 15 (FIG. 15 shows only a portion different from the control system configuration diagram shown in FIG. 3).

The image signal from the CCD camera 16 includes a V-sync signal (vertical synchronization signal) indicating the beginning of one screen and an H-sync signal (horizontal synchronization signal) indicating the beginning of one scanning line. I have. The synchronization signal separation circuit 201 converts this into V-sync and H-sy.
After separating nc, it is input to the image processing circuit 202. The image signal from the CCD camera 16 is supplied to the comparator 2
03 is input. The comparator 203 compares the signal with a predetermined threshold level signal and inputs a signal having a predetermined threshold level or more to the image processing circuit 202 as a bright spot detection signal. A clock circuit 204 that generates a sampling clock is connected to the image processing circuit 202. The image processing circuit 202 has a function of counting a sampling clock signal, H-sync, and a bright spot detection signal from the comparator 203. .

The count number of the sampling clock is H-sy.
It is cleared when nc is input, and the count number of H-sync and the bright spot detection signal is cleared when V-sync is detected. According to this relationship, the count number of the sampling clock can represent the x coordinate of the image, and the count number of H-sync can represent the y coordinate of the image. The count number of the sampling clock can be represented as the number of bright spots detected in one image. However, the coordinates and the number of the bright spot in this case represent the bright spot end (the bright spot edge). The information of these bright spots is sequentially stored in the data memory. And, like the previous example,
Whether the stored number of bright spot edges falls within a predetermined stock capacity (STEP-6), the distribution of bright spot edges is determined by the set number of lines LN
Is determined (STEP-17), information on the concentrated bright spots is deleted, the bright spot position is calculated, and the index image is specified. If the bright spot position is directly detected from the image signal from the CCD camera 16 in this way, the processing can be performed quickly, and alignment detection with higher accuracy can be performed.

As described above, according to the present invention,
Even when a large number of bright spots are detected on the corneal surface by the scattered light, the identification of the alignment index image is facilitated by not performing the bright spot detection at the concentrated portion.
As a result, an erroneous determination of the alignment state can be suppressed. Further, the area of the memory for storing the bright spot information can be used more effectively.

[Brief description of the drawings]

FIG. 1 is a schematic external view of a non-contact tonometer according to an embodiment.

FIG. 2 is a main part configuration diagram of a control system of the non-contact tonometer according to the embodiment.

FIG. 3 is a main part configuration diagram of a control system of the non-contact tonometer according to the embodiment.

FIG. 4 is a diagram showing an example of a screen displayed on a TV monitor when an eye to be inspected is aligned in an appropriate state.

FIG. 5 is a diagram showing a positional relationship between five index images used as a basis for determining an alignment state.

FIG. 6 is a view showing a flowchart of an index image detection process of the apparatus.

FIG. 7 is a diagram illustrating a method of specifying an index image in distinction from a bright point group.

FIG. 8 is a diagram showing a first combination for specifying one of two index images when two are detected.

FIG. 9 is a diagram showing a second combination for specifying one of two index images when two are detected.

FIG. 10 is a diagram showing a third combination for specifying one of two index images when two are detected.

FIG. 11 is a diagram showing a fourth combination for specifying one of two index images when two are detected.

FIG. 12 is a diagram showing a fifth combination for specifying one of two index images when two are detected.

FIG. 13 is a diagram illustrating a positional relationship between index images when three index images are detected.

FIG. 14 is a diagram illustrating a positional relationship between index images when four or five index images are detected.

FIG. 15 is a diagram illustrating a modification example of bright spot detection.

[Explanation of symbols]

 7 Second alignment target projection optical system 7a to 7d Light source 10 Observation optical system 16 CCD camera 30 First alignment target projection optical system 31 Light source 70 Control circuit 71 Image processing circuit 74 X-axis motor 75 Y-axis motor 76 Z-axis motor

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[Procedure amendment]

[Submission date] October 23, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art In an ophthalmologic apparatus such as an eye refractive power measuring apparatus and a non-contact tonometer, the measurement is performed by adjusting the alignment of a measuring optical system of the apparatus with respect to an eye to be examined in a predetermined positional relationship. The alignment mechanism detects an alignment target projected on the cornea, by controlling the driving of the moving means for moving the device on the basis of the detection information, automatically is proposed one which alignment adjustment or tracking Have been. The alignment index used for the drive control of the apparatus projects an index light beam from the front of the subject's eye to form a bright point at the apex of the cornea, and projects a plurality of alignment indices based on the positional relationship of the bright points formed on the cornea. In some cases, the center of the cornea is detected.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003]

However, a large number of scattered lights appear as bright spots on the corneal surface due to the condition of the corneal surface, other light-emitting materials (fluorescent lamps, etc.) and the tears of the subject. in addition there is a Ukoto, which may interfere with the center of the cornea detected without indistinguishable of the alignment index. In such a case, the device may determine the wrong alignment state,
The alignment itself cannot be detected. In the case where the bright spot information is sequentially stored in the memory, if a large number of bright spots are detected by the scattered light, it may exceed the allowable range of the memory, and the detection may be stopped halfway.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

The measuring section 4 also moves in the left-right direction (X direction) and the front-back direction (Z direction) with respect to the main body section 3. These movements are performed not by the joystick 5 but by an X-axis motor and a Z- axis motor whose driving is controlled by a control circuit described later.

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

Claims (7)

[Claims] 1. An ophthalmologic apparatus, comprising: a measuring unit for inspecting and measuring an eye to be inspected; aligning the measuring unit at a predetermined position with respect to the eye to be inspected; Index projection means for projecting,
A bright spot detecting means for detecting a bright spot having a brightness level equal to or higher than a predetermined brightness level formed on the cornea to be inspected; an irregular bright spot detecting means for detecting an irregular bright spot based on the detected bright spot information; An ophthalmologic apparatus comprising: movement instruction means for instructing the eye to move the measurement unit based on bright spot information excluding regular bright spots. 2. The ophthalmologic apparatus according to claim 1, wherein the irregular bright spot detecting means includes an irregular bright spot detecting means for determining whether or not the bright spot detected by the bright spot detecting means has an abnormal distribution in a predetermined area. An ophthalmologic apparatus, comprising: a determination unit configured to determine a bright spot as an irregular bright spot. 3. The ophthalmologic apparatus according to claim 1, wherein the irregular bright spot detecting means determines whether or not the detected number of bright spots exceeds a predetermined amount, and the irregular bright spot detecting means includes: Second determining means for determining whether the distribution of points is within a predetermined frame, wherein the number of bright spots exceeds a predetermined amount by the first determining means and the distribution of bright spots is determined by the second determining means. An ophthalmologic apparatus characterized in that when it is determined that the subject is within the frame, the bright spots counted up and down from the eye to be examined to a position where the predetermined quantity is reached are irregular bright spots. 4. The ophthalmologic apparatus according to claim 1, wherein, if effective information is not obtained as a result of excluding the irregular bright spot detected by the irregular bright spot detecting means, the movement instructing means performs the preceding operation. An ophthalmologic apparatus for instructing movement based on bright spot information obtained in step (a). 5. The notifying means for notifying, when effective information is not obtained as a result of excluding the irregular bright points detected by the irregular bright point detecting means, of the ophthalmologic apparatus according to claim 1. An ophthalmologic apparatus comprising: 6. The ophthalmologic apparatus according to claim 1, wherein the irregular bright spot detecting means stores a location information of the detected bright spot, and the stored bright spot location information is a predetermined amount. First determining means for determining whether or not the bright spot position information exceeds a predetermined amount; and further determining whether or not the distribution of the bright spots is within an area of a predetermined size. A second determining means for determining, and when the distribution of the bright spot position is determined to be within a predetermined size, the distribution area of the bright spot position is determined to be an irregular bright spot area. An ophthalmologic apparatus comprising: a regular bright spot area determining unit. 7. The ophthalmologic apparatus according to claim 1, further comprising: control means for controlling movement of the measurement unit by a movement means based on a movement instruction signal of the movement instruction means.